JP2005308571A - Diffused light measurement device and its measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a diffused light measuring device capable of acquiring an accurate measured value. <P>SOLUTION: This diffused light measuring device is provided with a sensor C for confirming the position of regularly reflected light to the emission surface spread on the prolongation of an integrating sphere A side face for removing the regularly reflected light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus having an integrating sphere for measuring the amount of diffused light of a reflecting object, and a measuring method thereof.

  In recent years, the demand for forming an optical system with a smaller number of optical surfaces has increased, and it has become essential to make the optical surface a free-form surface in order to ensure performance. In order to create a free-form surface, the conventional method of polishing centering around the rotation axis cannot be applied, and a method of cutting along a desired surface shape is mainly used. In this case, roughness and scratches are likely to remain on the optical surface, which is considered to cause more diffuse light. Therefore, it is necessary to quantitatively confirm the roughness on the free-form surface and the amount of scratch diffusion.

  Conventionally, when measuring the amount of diffused light of an object, the same measuring apparatus and measuring method as those used for spectrocolorimetric measurement of a reflecting object are used. FIG. 4 is an apparatus diagram generally used when performing spectral colorimetry of a reflective object (Non-Patent Document 1). These devices comprise an opening Ai for incident light to enter the integrating sphere A, a measurement sample holding part As, a light receiver Ad for detecting diffused light, and an emission part Ao for removing specularly reflected light IR. The emission part Ao is not limited to the optical trap part but may be an opening. Moreover, the schematic of the holding part of a general measurement sample was described in FIG. In many cases, a measurement sample is applied from the outside of the integrating sphere and held so as to be pressed down, and the measuring sample is fixed in a certain direction with respect to the integrating sphere A.

  During the measurement of diffused light, light is made incident from the aperture Ai for incident light, the specularly reflected light IR from the measurement sample surface escapes from the exit Ao to remove it, and the diffused light is captured by the inner wall of the integrating sphere, The intensity is detected by a light receiver.

The calibration of the absolute value of the diffusion intensity is performed by replacing the common standard white surface and the measurement sample and measuring the ratio with the diffusion intensity.
JIS Handbook Optics 1994 Z8722

  In an apparatus that measures the amount of diffused light from a reflecting object, ideally, the exit part Ao for removing specularly reflected light is small enough that leakage of diffused light does not become a problem, and the reflected light from the measurement sample surface is specularly reflected. It is desirable to be fully concentrated in the direction. However, in reality, the exit part Ao for removing specularly reflected light needs a diameter with a certain margin for reasons such as adjustment problems, and the reflected light from the measurement sample may be diffused light depending on its surface condition. It is distributed widely around the specular reflection light. Therefore, the amount of diffused light around the regularly reflected light that is emitted cannot be ignored.

  FIG. 6 is a conceptual diagram in which the intensity distribution of the specularly reflected light that has passed through the exit portion is shown with respect to the position on the exit surface. FIG. 6A shows the direction of the specularly reflected light at the center of the exit surface. In this case, FIG. 6B shows a case where the direction of specularly reflected light does not coincide with the center of the exit surface.

  From the comparison between FIG. 6 (a) and FIG. 6 (b), the amount of emitted light, that is, the amount of diffused light captured by the inner wall of the integrating sphere is determined by whether or not the direction of specularly reflected light coincides with the center of the exit surface. It can be seen that there is a difference. However, in the conventional diffused light amount measuring device, there is no means for confirming the relationship between the exit surface and the position of the specularly reflected light, and an accurate value cannot always be measured.

  Further, in the measurement sample holding format in the conventional measurement apparatus, the measurement sample is fixed and the inclination thereof cannot be adjusted. Therefore, even if the direction of the specularly reflected light does not coincide with the center of the exit surface as shown in FIG. 6B, there is no means for correcting it.

  Moreover, the shape of the measurement sample is limited to a flat plate, and in the shape having a curvature, the specularly reflected light diffuses and cannot be sufficiently emitted from the emission part Ao.

  The diffused light measuring device using the integrating sphere of the invention of claim 1 has a mechanism for confirming the position of the specularly reflected light with respect to the exit surface extending on the extension of the integrating sphere side surface for removing the specularly reflected light. It is a feature.

  According to a second aspect of the present invention, in the first aspect of the invention, the mechanism for confirming the position of the regular reflection light with respect to the position of the exit surface for removing the regular reflection light is a fixed sensor comprising a two-dimensional array. It is characterized by that.

  According to a third aspect of the present invention, in the first aspect of the present invention, the means for confirming the position of the regular reflection light with respect to the exit surface for removing the regular reflection light is a sensor that scans two-dimensionally. Yes.

  The invention of claim 4 is characterized in that, in the invention of claim 1, the distribution of intensity corresponding to the position in the exit surface for removing regular reflection light is measured.

  The invention of claim 5 is characterized in that, in the invention of claim 1, it has a mechanism capable of adjusting the normal direction of the measurement sample surface.

  According to a sixth aspect of the invention, in the fifth aspect of the invention, when the measurement sample surface is a concave surface, the measurement sample surface is focused on the focal length position of the measurement sample surface outside the integrating sphere with respect to the incident light opening. It is characterized by arranging a condensing lens which is an anamorphic optical system connecting the two.

  According to a seventh aspect of the present invention, in the apparatus for measuring a diffused light amount of the reflecting object according to the fifth aspect of the invention of the fifth aspect, when the measurement sample surface is a convex surface, the integration is performed with respect to the opening for incident light. A condensing lens, which is an anamorphic optical system that focuses on the focal length position of the virtual image space of the measurement sample surface, is arranged outside the sphere.

  The apparatus for measuring the amount of diffused light of a reflecting object according to the present invention has a mechanism for confirming the position of specularly reflected light with respect to the position of the exit surface extending on the extension of the integrating sphere side surface for removing specularly reflected light. It can be confirmed whether the reflected light is arranged at an appropriate position on the exit surface, and an accurate measurement value can be obtained. In addition, by having a mechanism for measuring the intensity distribution of regular reflection light corresponding to the position of the exit surface for removing regular reflection light, the amount of diffused light spreading around the regular reflection light can be measured.

  In addition, the apparatus for measuring the amount of diffused light of a reflecting object according to the present invention has a mechanism that can adjust the normal direction of the measurement sample surface, so that the position of specularly reflected light in the exit surface can be adjusted appropriately. It is possible to always obtain an accurate and highly reproducible measurement value.

  In addition to the apparatus for measuring the amount of diffused light of a reflecting object according to the present invention, an anamorphic optical system that focuses on the focal length position of the measurement sample surface outside the integrating sphere with respect to the opening for incident light. By arranging this condenser lens, even when the measurement sample surface has a curvature, it becomes possible to remove the specularly reflected light as parallel light from the emitting part, and the amount of diffused light can be measured accurately.

  FIG. 1 is an apparatus diagram for measuring the amount of diffuse light of a reflecting object according to the present invention. The integrating sphere A has an aperture Ai for incident light, an emitting part Ao for emitting specularly reflected light, a measurement sample base As, and a light receiver Ad. A sensor C consisting of a removable two-dimensional array corresponding to the position of the exit surface is located around a straight line connecting the intersection of the sample and the center of the exit surface extending on the side of the integrating sphere to exclude specular reflection. Has been placed. In this example, a CCD was used as the sensor.

  FIG. 2 shows a measurement sample stage As in the measurement apparatus of the present invention. There is an opening in the wall of the integrating sphere A, and the measurement sample stage As has a protruding table with a size smaller than the opening on the base that is shaped to cover the opening along the wall of the integrating sphere. In the fixed state, it fits into the opening of the integrating sphere. It has multiple adjusting screws As-2 to adjust the normal direction of the sample surface.

  In the apparatus for measuring the diffused light amount of the reflecting object according to the present invention, the sensor C comprising a removable two-dimensional array corresponding to the position of the exit surface is used to detect the specularly reflected light with respect to the position of the exit surface for removing the specularly reflected light. The position can be confirmed. As a means for confirming the position of the specularly reflected light with respect to the position of the exit surface, in addition to the sensor C having a two-dimensional array, a method of directly confirming with eyes through a ground glass or a sensor that scans two-dimensionally may be used. However, a sensor that scans two-dimensionally has a mechanical mechanism that associates the scanning position with the position of the exit surface.

  If the specular reflection direction does not match the straight line connecting the intersection of the incident light and the measurement sample and the center of the exit surface for removing the specular reflection light from the information from sensor C, the adjustment screw on the measurement sample base By adjusting As-1, the specular reflection direction can be moved to an appropriate direction. In addition, since the sensor C can also obtain an intensity distribution corresponding to the position in the exit surface, it is possible to relatively measure the amount of diffused light spreading around the specularly reflected light.

  As described above, after the specular reflection direction is optimally arranged, the sensor C is removed and the amount of diffused light is measured in order to prevent the reflected light generated on the surface of the sensor C from returning to the integrating sphere.

  FIG. 3 shows a measurement apparatus diagram when the measurement sample surface is concave. In addition to the apparatus for measuring the amount of diffused light of the reflecting object of the present invention, a condensing lens B of an anamorphic optical system is disposed outside the integrating sphere with respect to the opening for incident light. By arranging the condenser lens, the specular reflection light can be made parallel light, and the specular reflection can be removed from the emission part even when the measurement sample is concave with respect to the incident light. However, the condensing lens needs to be an anamorphic optical system. The shape of the anamorphic optical system is such that the light incident on the integrating sphere has an incident angle φ, and the focus position generated due to the difference in the power received by the incident light in the in-plane direction of FIG. The shape must correspond to the difference.

  The same can be said for the measurement sample surface even on the convex surface.

Explanatory drawing which shows the measuring apparatus of a diffused light by this invention Example. Explanatory drawing which shows the measurement sample stand by this invention Example. Explanatory drawing which shows the measuring apparatus in case a measurement sample surface is a concave surface by the Example of this invention. Explanatory drawing which shows the measuring apparatus of the conventional diffused light quantity. Explanatory drawing which shows the measurement sample holding | maintenance part in the measuring apparatus of the conventional diffused light quantity. Explanatory drawing which shows intensity distribution of the regular reflection light which passed out from the emission part.

Explanation of symbols

I Incident light
IR reflected light
A integrating sphere
As measurement sample stage or measurement sample holder in integrating sphere
Ad receiver in integrating sphere
Ai Aperture for incident light
Ao Regular reflection light emission part
Adjustment screw on As-1 measuring table pull sample S Measurement sample
C sensor
B Condenser lens

Claims (7)

  In a device that measures the amount of diffused light from a reflecting object using an integrating sphere, it has a mechanism for confirming the position of the specularly reflected light with respect to the exit surface extending on the extension of the side of the integrating sphere to exclude specularly reflected light. A diffused light measuring device.   2. The apparatus for measuring the amount of diffuse light of a reflecting object according to claim 1, wherein the mechanism for confirming the position of the regular reflection light with respect to the exit surface for removing the regular reflection light is a fixed sensor comprising a two-dimensional array. A diffused light measuring device characterized by being.   2. The apparatus for measuring the amount of diffuse light of a reflecting object according to claim 1, wherein the means for confirming the position of the specularly reflected light with respect to the exit surface for removing the specularly reflected light is a sensor that scans two-dimensionally. A diffused light measuring device characterized by the above.   2. The diffused light measuring device according to claim 1, wherein the diffused light measuring device measures a distribution of intensity corresponding to a position in an exit surface for removing specularly reflected light.   2. The diffused light measuring device according to claim 1, further comprising a mechanism capable of adjusting a normal direction of a measurement sample surface.   6. The apparatus according to claim 5, wherein when the measurement sample surface is concave, the focal length of the measurement sample surface outside the integrating sphere with respect to the incident light opening. A measuring device with a condenser lens that is an anamorphic optical system that focuses on the position.   6. The apparatus for measuring a diffused light amount of a reflecting object according to claim 5, wherein when the measurement sample surface is a convex surface, a virtual image space of the measurement sample surface outside the integrating sphere with respect to the opening for incident light. Measuring device which arranges a condensing lens which is an anamorphic optical system which focuses on the focal length position of.

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